"Let's start to initiate the path of dialogue, but at the same time tomorrow [Thursday] there is an EU summit and sanctions could be voted tomorrow if there is no de-escalation. I expect and hope that Russia will today tell us that there is a prospect for dialogue with a contact group," he said, referring to proposals to form a grouping of key players in the Ukraine crisis.

Fabius was speaking before hosting talks between his Russian, US, Ukrainian and other counterparts on the margins of a long-scheduled meeting on Lebanon in the French capital.

US Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov will meet face-to-face for the first time since the crisis escalated, after a conference in Paris attended by all five permanent members of the UN Security Council, diplomats organising the talks said.

Warning to Moscow
Fabius added that France had jointly elaborated a "crisis exit" plan with Germany, whose leader Angela Merkel has been more reticent than French officials to publicly raise the threat of sanctions on Russia.

Despite his toughly worded warning to Moscow, Fabius reiterated previous comments that France had no plan as yet to suspend deliveries of naval ships to Russia.

Meanwhile, Ukraine's ambassador told the UN atomic agency in a letter seen by Agence-France Presse on Wednesday that Ukraine is reinforcing security measures at its nuclear power plants in response to Russian threats.

"Illegal actions of the Russian armed forces on the Ukrainian territory and the threat of force amount to a grave threat to security of Ukraine with its potential consequences for its nuclear power infrastructure," Ihor Prokopchuk said.

"Under these circumstances, the competent authorities of Ukraine make every effort to ensure physical security, including reinforced physical protection of 15 power units in operation at four sites of Ukrainian [nuclear power plants]," Prokopchuk said in the letter to International Atomic Energy Agency chief Yukiya Amano.

Prokopchuk added however that the "consequences of the use of military force by the Russian Federation" against the former Soviet state "will be unpredictable".

"Numerous efforts of the government of Ukraine to establish bilateral contacts with the Russian counterparts have not been responded to so far," he said.

He urged Amano to "urgently raise the issue of nuclear security with the authorities of the Russian Federation." – Reuters